The present invention relates to a method of manufacturing a stator winding of a rotary electric machine, such as a vehicular alternator installed on passenger vehicles or trucks, and structure of a winding and a method of manufacturing the winding.
In recent years, it has been required to improve power generation performance of a vehicular alternator in accordance with an increase in current consumed by safety control apparatus. To meet the requirement, it is proposed to improve power output of a stator by increasing occupancy of the electric conductors in slots of the stator by regularly arranging U-shaped electric conductors in the slots. This kind of stator is disclosed in JP-A-2001-45721 (U.S. Pat. No. 6,314,780) and JP-B2-3118837 (U.S. Pat. No. 6,249,956), for example.
According to the method disclosed in JP-B2-3118837, breakage of an insulation film at a turn portion of a U-shaped electric conductor due to excess concentration of stress is reduced by increasing an inside dimension or diameter of the turn portion for some amount, even if an overall width of straight portions of the U-shaped electric conductor including a gap between them is small.
However, when the inside dimension of the turn portion is increased to reduce the breakage of the insulation films, an outside width of the turn portion increases for the amount. Therefore, in a stator winding constructed of the U-shaped electric conductors, the turn portions largely protrude from an outer circumferential end and an inner circumferential end of a stator core in a radial direction. As a result, the turn portions are likely to interfere with a housing located on an outer periphery of the stator and other components such as a rotor located radially inside of the stator.